Dark-field condenser for microscopes



March 20, 1934.- R, STRAUBEL 1,951,635

mak 'FIELD coNnENsER -For: urcnscorss 'Filed Feb. 20.' 19252` Patented Mar. 20,Y 1934` DARK-FIELD CONDENSER FOB MICROSCOPES Rudolf Str-anbei, Jena, Germany, assigner to linx Carl Zeiss, Jena, Germany Application February zo, 1932, sex-1.1 N. 594.341

In Germany March 10, 1931 BCIaims.

The invention concerns a darkeld condenser for microscopes, having only one reflecting surface, which distinguishes over the known condensers of this kind by a. specially simple form 5 and.V therefore can be manufactured at a c'omparatively low cost. The invention consists in that the reflecting surface of the condenser has approximately the form of an ellipsoid of revolution in the foci of which are placed the light source and the object, respectively. A corresponding toric or spherical form may be stituted for the said ellipsoidal one.

With respect to the fusion of the rays, condensers o; vthe said kind are required to have the light source, when in use, always assume one and the same position relatively to the reflecting surface. This condition is arrived at in the most simple manner by rigidly connecting the light source and the condenser. Flu-ther, the condenser may be improved by providing a variable diaphragm for restricting the aperture of the pencil of illumination rays, this diaphragm suitably being a tube which envelops the light source and is displaceable in the direction of the axis of revolution of the ellipsoid,

The accompanying drawing represents in elevation, in a central oros section, a constructional example of the condenser according to theinvention.

. In the said example, ahousing a encloses a glass block b. This glass block b has a silvered exterior surface c which'represents part of an ellipsoid, and a semispherical recess d the spherical centre 'of which coincides with one focus of the reflecting surface c. Part of the surface of subthe recess d is provided with a non-transparent.

layer e. To the housing a is connected a cylin# drical part f in which a tubular diaphragm g can be displaced by'means of a lever h guided by a helical slot i in the direction of the axis of revolution of the exterior surface c. The part f is surrounded' by another cylindrical part Ic which also has a guide slot l for the lever h. Both cylindrical parts f, k are closed by a lid m which in its turn is provided with a cylindrical part n receiving the Vholder o for an incandescent 'lamp focus of the reilecting surface.

p. Inordertoavoidtheillament beingsharplyimagedintheprepanontobe examined,thebulboi'thslamppisli8htly frosted.

When using the the lamp-holder o isclampedinthepartnbymeansofascrew q in such a mannercthat the incandescent iilament of thelampp comestolieinthespherical centre of the recess d. When in` this position, the incandescent lamp p is enveloped by the tubular diaphragm g. By shitting the lever Il. in the guide slotLtheape'rture ofthepencilof illumination rays is reduced by the dla guntilallraysaredowncompletely. The condenser isplacedwitnitsndm anche stage of the microscope, the part n projecting in the usual manner into the illumination aperture which is provided in any microscope stage. The object slide with the prepa.-l rationtobeexaminedispladonthenpper surface of the glass block b.

I claim: Y

1. A dark-field condenser for microscopes, having only one reflecting surface, this reiiecting surface having the form of an ellipsoid of revo lution, the condenser being adapted to receive in one focus of the reflecting surface'the object A tobeilluminatedsothatlightisconcentrated on this object when from the other focus.

2. A dark-field condenser forA microscopes, having only one reflecting surface, this reiecting surface having the form of an ellipsoid of revolution, the condenser'beng adapted to receiveY in one focus of the reflecting surface the object 90 to beilluminated,andalightsourcexedto the condenser, this light source in the other focus of the reflecting surface.

3. In a dark-held r according to claim 1, a tubular diaphragm attached to the condenser, the axis of the said tubularpdiaphragm being pary alleltotheaxisofthecondensenthesaidtubular diaphragm being le in the direction ofthesaidaxesandgoingrolmdthesaidother nunon# smaUBE-L. 

